In order to retain accommodated connecting terminals within a housing, locking lances are usually provided within the housing. In order to further improve the above mentioned locking of the connecting terminals within the housing, it has been proposed to insert a rear holder into a rear portion of the housing. The rear holder serves to prevent the connecting terminals from being removed. It has been further proposed to provide locking lances within the rear holder.
In general, a pair of housings each having a connecting terminals installed therein are coupled with each other, and the coupled condition is maintained by means locking mechanisms provided on the housings. Usually the rear holder does not have any roll in this coupling, and therefore the rear holder could not be locked sufficiently. Moreover, when a locking arm is provided on the housing, a size of the housing is liable to be large and a height of the housing is increased.
The applicant of the instant application has proposed, in Japanese Patent Applications Nos. 2002-57638 and 2003-3995, a locking mechanism in which a locking arm is provided on a rear holder coupled with one of a pair of housings and this housing is locked with the other housing by means of the locking arm. Then, the housing with which the rear holder is coupled is sandwiched between the rear holder and the other housing, and the assembly is hardly decomposed accidentally.